http://www.intel.com/update/departme...op/dt05001.pdf
probably a cnr slot, could be one of a couple others, via made their own expansion slot for a while, i dont know why they bother, any hardware for these is expensive and usually not any better. like the amr slot on some motherboards, supposed to be for less expensive modems that use system resources instead on having their own . big laugh, they are total crap.